Sjöormen-class submarine

HSwMS Sjöormen in August 1967

The Sjöormen class (Sea serpent) was a class of submarines built for the Swedish Navy in the late 1960s. They had a teardrop hull shape and were capable of diving to . At the time of their deployment they were regarded as one of the most advanced non-nuclear submarine-classes in the world, incorporating many new features including x-rudder and anechoic tiles. Both speed and underwater endurance was at this time very high for a conventional submarine. The submarines were retired by Sweden in the early 1990s. In the late 1990s, all five submarines were acquired by the Republic of Singapore Navy (RSN) and four were relaunched as the following modernisation and tropicalisation. The fifth was never relaunched as it was used for spare parts and subsequently scrapped in the 2000’s. As of November 2024, the Challenger-Class has been decommissioned.

Description

As built, the Sjöormen class were designed with a teardrop hull shape, based on the United States' . They had bow planes on the sail and their stern diving planes were configured in a x-shape.Template:Sfn They had a standard displacement of and when dived.Template:SfnTemplate:Refn The submarines had a waterline length of and a length overall of . They had a beam of and a draught of . The Sjöormen class was powered by a diesel-electric propulsion system composed of two Pielstick diesel engines providing power to an ASEA electric motor driving one shaft with a five-bladed propeller. The entire system was rated at . This gave the submarines a surfaced speed of and submerged. Designed for the confined waters of the Baltic sea, the vessels had an endurance of 21 days and a test depth of .Template:SfnTemplate:Sfn

As built the Sjöormen class were equipped with surface search radar and sonar.Template:Sfn The submarines were armed with four torpedo tubes located in the bow for surface attack and two torpedo tubes in the stern for either anti-submarine warfare or for naval mines. The Sjöormen class had a complement of 23 officers and enlisted.Template:SfnTemplate:Sfn

Swedish upgrades

In 1984–85, the Sjöormen class received upgraded Ericsson IBS-A17 fire control system and CSU-83 sonar suite. In 1992, refits began on Sjölejonet and Sjöhunden that improved their electronics and their towed sonar array.Template:Sfn

Ships

Ship name	Builder	Launched	Commissioned	Status
Template:HSwMS	Kockums	25 January 1967	31 July 1968	sold to Singapore as RSS Centurion
Template:HSwMS	Kockums	29 June 1967	16 December 1968	sold to Singapore as RSS Conqueror
Template:HSwMS	Karlskrona Navy yard	9 January 1968	28 February 1969	sold to Singapore as RSS Challenger
Template:HSwMS	Kockums	21 March 1968	25 June 1969	sold to Singapore as RSS Chieftain
Template:HSwMS	Karlskrona Navy yard	6 August 1968	15 September 1969	sold to Singapore as spare parts

Service history

The Sjöormen class were ordered by the Swedish Navy in 1961. The first boat in the class, Sjöormen, entered service in 1968. In 1992, two vessels in the class, Sjölejonet and Sjöhunden, underwent modernisation. The remaining three were supposed to remain in service until the became operational, but due to lack of funding, all were laid up in 1993.Template:Sfn

All five submarines were sold to the Republic of Singapore Navy (RSN) in the late 1990s and four entered service as the following modernisation and tropicalisation, while the fifth was used for spare parts and subsequently scrapped in the late 2000’s.

References

Notes

Citations

Bibliography

External links

• Official Kockums website on the Challenger class submarines
• Covert Shores